Preparation of catalysts of predetermined pore size distribution and pore volume

ABSTRACT

An improved process for the production of catalysts comprised of a metal hydrogenation component, or components, composited with high pore volume alumina, with pores of narrow pore size distribution, wherein macropore volume is drastically reduced by improved extrusion techniques. An alumina hydrogel paste is extruded through a die to form spaghetti-like extrudate shapes by application of sufficient torque, suitably from about 25 to about 55 inch-pounds, preferably from about 40 to about 50 inch-pounds, to eliminate much of the macropore volume, i.e., pores greater than 400A, which greatly improves the activity maintenance of the catalyst. The extrudates can, if desired, be shaped into other forms, suitably spheres. The improved process also embodies a technique for increasing the intrinsic activity of these and other catalysts by special impregnation techniques which provides better dispersion of the metal hydrogenation component, or components, throughout the catalyst.

RELATED APPLICATIONS

This is a continuation-in-part of application Ser. Nos. 646,490 and646,491 by Willard H. Sawyer, et al, filed Jan. 5, 1976, now U.S. Pat.No. 4,016,106 and U.S. Pat. No. 4,016,107 issued on Apr. 5, 1977herewith incorporated by reference. Reference is also made to now Ser.No. 646,492, filed on even date herewith, to which the instantApplication is related.

Processes for the preparation of synthetic forms of alumina for use incatalytic processes have been known for many years. Albeit alumina canbe so prepared in very pure form, at controlled conditions to provideparticular characteristics not possessed by natural alumina, fewprocesses are available for the formation of alumina of preselected, orcontrolled, large pore size distribution with high pore volume,particularly high pore volume alumina with large pores of narrow poresize distribution.

U.S. Pat. Nos. 3,977,961 and 3,977,962 which issued Aug. 31, 1976, e.g.,describes the preparation of catalysts from alumina formed by theneutralization of an aluminum salt solution with ethylene oxide atcontrolled conditions. These catalysts are characterized as havingproperties inclusive of a large number of pores in the 100-275A(Adsorptomat) pore size diameter range, and very high pore volume. Theyhave proven particularly useful in the production of clean liquidproducts by the hydroconversion of the 1050° F. + materials contained inunconventional heavy crudes and residua, which materials areparticularly difficult to treat because they have (1) very highConradson carbon (i.e., "Con carbon") or carbon-hydrogen ratios (i.e.,relatively high carbon and low hydrogen content), (2) very high metalscontent, particularly as regards the amount of nickel and vanadium, (3)an ultra-high content of materials boiling above 1050° F., e.g.,asphaltenes, and (4) contain considerable amounts of sand and scale.

Despite the admirable success of these catalysts, it was nonethelessfelt that yet better activity, and improved activity maintenance weredesirable. Moreover, albeit the ethylene oxide neutralization method forthe preparation of these catalysts was acceptable, certain difficultiesmade it desirable to find a commercial alternate for the production ofthese catalysts. One problem that favored the development of analternate process was that ethylene chlorohydrin, a very hazardouschemical, was evolved as a by-product in the ethylene oxideneutralization process. The elimination of this hazard requiredadditional treating facilities, which proved to some degree a burden onthe process. Equally as important, a strict process regimen was requiredto produce the most active catalysts. This too, to some degree, proved aburden cumulative with the former. The desire thus arose for analternate process.

It was then discovered that high pore volume, large pore catalysts couldbe produced by a new and improved polymer extension technique asdisclosed and claimed in pending application Ser. Nos. 646,490 and646,491 by Willard H. Sawyer et al., now U.S. Pat. Nos. 4,016,106 andU.S. Pat. No. 4,016,107, respectively and application Ser. No. 646,492by Harry E. Robson, now U.S. Pat. No. 4,016,108 which issued Apr. 5,1977. The disclosed process of Sawyer et al and Robson is an improvementover an earlier method for the preparation of large pore catalystswherein alumina of pore volume ranging from about 20 A to 20,000Adiameter, and higher, is prepared by the addition of a wide number ofwater soluble organic polymers ranging from low molecular weight to veryhigh molecular weight materials, either dissolved in the solution usedto prepare the gel or dissolved or dispersed within the hydrous mass ofgel after it has been precipitated. This method, and the disclosuregenerally of alumina precipitation from aqueous alkaline solutions,supra, is disclosed in U.S. Pat. No. 3,417,028. Reference is also madeto the Journal of Catalysis, Vol. I, Pages 547-563 [1962], "The Controlof the Pore Volume and Pore Size Distribution in Alumina and Silica Gelsby the Addition of Water-Soluble Organic Polymers," by Z. Basmadjian, G.N. Fulford, B. I. Parsons, and D. W. Montgomery.)

The polymer extension method disclosed by Sawyer et al and Robsonrequires as its starting point the precipitation of a hydrous form ofalumina from solution by adding to an aqueous alkaline aluminatesolution a quantity of an inorganic acidic compound having an anion thatforms an aluminum salt that is soluble in an alkaline solution. Forexample, a solution of aluminum oxide trihydrate dissolved in a strongalkali, e.g., NaOH, added to a mineral acid or the aluminum salt of astrong mineral acid, e.g., Al₂ (SO₄)₃, such that at the end point thesolution is at pH ranging from about 8 to 12, generally from about 9 to10, causes the precipitation of a hydrous form of alumina from solution.Whereas this technique per se, and an eariler polymer extension process,supra, for forming alumina were known to the prior art, the polymerextension method of Sawyer et al and Robson differed drasticallytherefrom, inter alia, in that high pore volume alumina, with pores ofnarrow pore size distribution, could be formed by adsorption into thepores of the alumina hydrogel specific concentrations of water solublepolymers containing from 2 to about 24 monomer units from the groupconsisting of (a) polyethylene glycols, (b) polypropylene glycols, and(c) polyethylene amines. In contrast to the polymer extension process ofSawyer et al and Robson, inter alia, most of the pore volume of thealumina prepared by the earlier polymer extension method was in therange of 1000A diameter or greater, with no means for concentrating porevolume in any particular range, much less within a narrower range ofpore sizes. Moreover, the polymers used as pore volume extenders in theearlier polymer extension process were consumed in the calcination stepand hence, due to the cost of the polymer, the process was necessarilydebited; and further the smoke and fumes produced on burning the polymerduring calcination created additional burdens on the process.

The process disclosed in said Sawyer et al. and Robson patents, in anyevent, though admirably suitable for the production of high pore volumealumina, with pores of narrow pore size distribution, is nonethelesssusceptible of further improvement. Thus, though many of the problemsassociated with the ethylene oxide process are eliminated, the catalystproduced in this process are not consistently as active, or possessed ofas high activity maintenance, as thos produced in the ethylene oxideprocess. This process too, like the ethylene oxide process, alsorequires a too carefully controlled regimen of the conditions ofoperation to produce the most active catalyst species. Furtherimprovements in the polymer extension process are therefore yetdesirable.

A primary objective of the present invention, therefore, is to supplythis need.

A particular object is to provide further improvements in polymerextension processes, particularly the polymer extension process ofSawyer et al and Robson, and to make such process yet more useful in thepreparation of catalysts suitable for hydrocarbon conversion reactions,especially reactions involving the hydroconversion of the 1050° F+hydrocarbon portion of heavy crudes and residua.

A further specific object is to supply a new and improvedpolymer-extension process, particularly one suitable for the preparationof catalysts useful in converting the 1050° F.+ hydrocarbon portion offeeds comprising heavy crudes and residua to useful lower boilingproducts while simultaneously producing appreciable Conradson carbon(Con carbon) reduction, hydrodesulfurization, hydrodenitrogenation anddemetallization of the feeds.

A yet further and yet more specific object is to provide a process byvirtue of which the hydrodesulfurization activity, hydrodesulfurizationactivity maintenance, and demetallization activity of catalysts producedby the polymer extension process of Sawyer et al and Robson and otherscan be further increased.

These and other objects are achieved pursuant to the practice of theinvention which relates to improvements in a process for the treatmentof a hydrogel by contact thereof with an aqueous solution containingfrom about 10 to about 20 percent, preferably from about 15 to about 20percent, by weight, of a water soluble polymer containing from 2 toabout 24, preferably from about 4 to about 8 monomer units, from thegroup consisting of (a) polyethylene glycols, (b) polypropylene glycols,and (c) polyethylene amines, sufficient to add said polymer to thehydrogel in polymer:alumina concentration ranging from about 0.5:1 toabout 4:1, preferably from about 1:1 to about 2:1, to develop largepores, of relatively narrow pore size distribution, subsequent to whichthe alumina hydrogel is dried, formed into a paste of proper extrusionconsistency and the paste then extruded through a die to formspaghetti-like extrudate shapes by application of sufficient torque,suitably from about 25 to about 55 inch pounds, preferably from about 40to about 50 inch pounds, to eliminate much of the macropore volume,i.e., pores greater than 400A (i.e., 400A+) and thereby improve theactivity maintenance of the catalyst.

The process also embodies a technique for increasing the intrinsicactivity of these and other catalysts by special impregnation techniqueswhich provides better dispersion of the metal hydrogenation component,or components, throughout the catalyst.

In a preferred embodiment the process involves the following steps:

1. Alumina, as a hydrogel, is precipitated from an alkaline solution ata pH ranging from about 8 to 12, preferably 9 to 10, by adding to ahydrous form of alumina in aqueous alkaline solution, an inorganic acidor aluminum salt of an inorganic acid consitituted in part of an anionsoluble in an alkaline medium. The alumina is normally precipitated bycombining solutions, (a) a first of which contains an alkali metalaluminate, e.g., NaAlO₂, and (b) a second of which contains a strongmineral acid or an aluminum salt of a strong mineral acid, the anionportion of which is soluble in an alkaline solution, e.g., Al₂ (SO₄)₃.Silica can be added, if desired, to ultimately produce a "glassy"alumina or to increase the resistance of the catalyst to sintering. Thetemperature of precipitation ranges generally from about 15° F. to about120° F., and preferably from about 32° F. to about 70° F. Suitably, theconcentration of alumina contained within the sum-total of the solutionranges from about 1 to about 5 weight percent, preferably from about 2to about 3 weight percent.

2. The precipitated alumina hydrogel, a microcrystalline substance, in agel matrix, ranging from about 30A to about 40A in crystallite size, ispreferably washed with water or aqueous solution suitably at ambienttemperature or temperature or temperatures ranging from about 70° F. toabout 85° F., to remove essentially all of the soluble salt, e.g., Na₂SO₄. The removal of a large part of the sulfate from the aluminahydrogel is essential to achieve high surface area and good catalyticactivity in the finished catalyst, and preferably essentially all of thesulfate is removed from the hydrogel.

3. In a pore volume extending step, a "pore volume extending" agentcomprising a water-soluble polymer containing from about 2 to about 24monomer units, preferably from 4 to about 8 monomer units, from thegroup consisting of (a) polyethylene glycols, (b) polypropylene glycols,and (c) polyethylene amines is then added to the partially washedhydrogel, suitably during the washing step, or the hydrogel furthercontacted or washed with a solution of the polymer. In either event, thehydrogel is contacted with an aqueous solution containing from about 10weight percent to about 20 weight percent, and preferably from about 15weight percent to about 20 weight percent of the polymer, such that thepolymer solution is absorbed into the pores of the hydrogel. Suitably,the hydrogel is contacted or washed at ambient temperature, or at atemperature ranging from about 70° F. to about 85° F.

The final pore volume, and pore volume distribution, of the finishedalumina is principally determined by the amount of polymer, or porevolume extender, added to the hydrogel during the pore volume extendingstep. In contacting or washing the hydrogel, the water within thehydrogel is displaced by polymer solution, and the more concentrated thepolymer within the solution the greater the amount thereof which can beexchanged into the hydrogel. Preferably, the water is displaced untilthe weight ratio of polymer-alumina within the hydrogel ranges fromabout 0.5:1 to about 4:1, and preferably from about 1:1 to about 2:1.Suitably, the exchange is accomplished by blending the components,stirring and filtering, with repetition of these steps until thehydrogel contains the desired amount of polymer, or by initialfiltration of the gel with subsequent washing of the gel with polymersolution while the gel is contained on the filter.

If desired, the hydrogel can, at this time, be impregnated with acatalytically active amount of a metal hydrogenation component, or metalhydrogenation components, suitably a Group VIB or Group VIII metal(preferably a non-noble metal), or both (Periodic Table of the Elements,E. H. Sargent and Co., copyright 1962 Dyna-Slide Co.). The metalhydrogenation component can be incorporated into the hydrogel during thepore volume extending step, if desired, by the addition of solublecompounds, or salts, of such metals. Molybdenum of Group VIB and cobaltor nickel of Group VIII are preferred metals, particularly an admixtureof these metals. Preferably, however, the hydrogenation component, orcomponents, is added subsequent to calcination of the material, assubsequently discussed.

4. The polymer containing hydrogel is dried, suitably at temperaturesranging from about 85° F. to about 350° F., and preferably from about212° F. to about 250° F., to form a gel. In this step, the porestructure of the hydrogel is set and the hydrogel converted intoboehmite. The boehmite, after drying, exists as a granular substancewhich can, by proper adjustment of its solids (or liquid) content, beformed into various shapes, e.g., extrudates or spheres.

5. The polymer is then removed from the boehmite shapes, i.e.,extrudates or spheres, preferably by contact and extraction with asuitable solvent. The C₄ + alcohols, notably the C₆ and C₆ + alcohols,are highly preferred for extraction and removal of the polymer.

6. The boehmite shapes, i.e., extrudates or spheres, after removal ofthe polymer are then dried, calcined and preferably at this timeimpregnated with a metal hydrogenation component, or components.Suitably a catalytically active amount of a metal hydrogenationcomponent, or metal hydrogenation components, notably a Group VIB orGroup VIII metal (preferably a non-noble metal), or both (Periodic Tableof the Elements, E. H. Sargent and Co., copyright 1962 Dyna-Slide Co.),is incorporated into the alumina shapes by impregnation thereof withsolutions of soluble compounds, or salts, of such metals. In theimpregnation, the metal hydrogenation component, or components, isimpregnated into the dried, calcined alumina from an aqueous or C₁ -C₃alcohol solutions, and preferably C₄ + alcohol solutions, and then driedat a very slow rate, prior to a final calcination, to enhance catalystactivity.

Catalysts of both extrudate and spherical shape have been foundparticularly useful in the hydroprocessing of unconventional whole heavycrudes and residua, particularly extrudate and spherical catalystsranging from about 1/50 to about 1/8 inch, preferably from about 1/32 toabout 1/8 inch, and more preferably from about 1/32 to about 1/16 inchparticle size diameter. Pursuant to the practice of this invention,catalysts in the shape of very smooth hard extrudates and spheres can beformed. These catalysts are particularly useful as fixed beds inhydroprocessing processes, largely because of the uniformity of theparticles and roundness of the spheres which considerably reducepressure drop as contrasted with the use of catalysts of more irregularshape which tend to pack more closely together. The catalysts are alsoespecially suitable for use in liquid fluidized or ebullating beds. Thediffusion limitations concomitant to the hydroprocessing of the highmetals content whole heavy crudes and residua are largely overcome, poreblockage is suppressed, and there is a significant beneficial effect inthe ability of the smaller particle size catalyst to desulfurize,demetallize, and denitrogenate such feeds. High concentrations of themetals, notably nickel and vanadium, are removed from such feeds duringthe hydroconversion reaction, and yet good catalyst activity maintenanceis achieved. A high rate of hydrodesulfurization is attained.

In the catalysts of this invention, there is a direct relation betweenparticle size and pore size. The catalysts of this invention include acombination of properties:

a. when the catalyst is of size ranging from about 1/50 inch up to 1/25inch average particle size diameter, as follows:

    ______________________________________                                                       Typical   Preferred                                            ______________________________________                                        Surface Area, .sup.(1) m.sup.2 /g                                                              200-500     225-325                                          Pore Volume, .sup.(2) cc/g                                                                     0.5-1.5     0.7-1.1                                          Pore Size                                                                     Distributions, cc/g .sup.(3)                                                  100-200A         >0.3        >0.4                                             200-400A          >0.05      >0.1                                              400A+           <0.2        <0.1                                             1000A+           <0.1         <0.05                                           ______________________________________                                         .sup.(1) Measured by single point adsorption using BET equation.              .sup.(2) Measured by filling of the pores with nitrogen in a single point     measurement.                                                                  .sup.(3) Measured by combination of Digisorb Desorption and Mercury           Intrusion.                                                               

b. when the catalyst is of size ranging from about 1/25 inch to about1/8 inch average particle size diameter, as follows:

    ______________________________________                                                       Typical   Preferred                                            ______________________________________                                        Surface Area, .sup.(1) m.sup.2 /g                                                              200-500     250-350                                          Pore Volume, .sup.(2) cc/g                                                                     0.7-1.7     0.8-1.3                                          Pore Volume                                                                   Distributions, cc/g.sup.(3)                                                   100-200A         >0.3        >0.4                                             200-400A          >0.05      >0.1                                              400A+           <0.2        <0.1                                             1000A+           <0.1         <0.05                                           ______________________________________                                         .sup.(1) Measured by single point adsorption using BET equation.              .sup.(2) Measured by filling of the pores with nitrogen in a single point     measurement.                                                                  .sup.(3) Measured by combination of Digisorb Desorption and Mercury           Intrusion.                                                               

In all forms of the catalysts, the pore volumes resultant from pores of50A, and smaller, i.e., 50A-, and those resultant from pores of 400A,and larger, i.e., 400A+, are minimized. The small pores are ineffectivein producing effective hydrodesulfurization, and the large pores permitall too rapid loss of catalyst activity. The surface areas and porevolume of the catalysts are interrelated with particle size and poresize distributions. Surface areas range generally at least about 200 m²/g to about 500 m² /g, and preferably at least about 225 m² /g to about350 m² /g, with pore volumes ranging from about 0.5 to about 1.7 cc/g,and preferably from about 0.7 to about 1.3 cc/g (B.E.T.).

In their optimum forms, the absolute pore size diameter of the catalyst,dependent on particle size, is maximized within the 100-200A and200-400A ranges, respectively. The 100-200A range is believed to providea maximum of active sites for effecting hydrodesulfurization, and the200-400A range is found to provide high demetallization. It is notpractical, of course, to eliminate the presence of all pores of sizeswhich do not fall within these desired ranges, but in accordance withthis invention, it is practical to produce catalyst particles, inclusiveof those of extrudate and spherical shapes, having absolute pore sizediameters highly concentrated within these desired ranges.

These and other features of the invention will be better understood byreference to the attached drawing, and to the following detaileddescription of a highly preferred process for the preparation ofextrudates and spherical catalysts in accordance with this invention.

In the drawing:

The FIGURE schematically depicts a preferred flow plan, starting withthe blending of the hydrogel and the polymer containing solvent andending with the finished catalyst.

Referring generally to the FIGURE for an overview of the process, thereis depicted a flow plan suitable for use in the formation of aluminaextrudates or spheres comprising the combination of a blender 10 whereina previously washed, moist alumina hydrogel, as formed in Steps 1 and 2,supra, is blended with makeup polymer and recycle polymer fordisplacement of water and incorporation of polymer within the hydrogel,as in Step 3, supra; a spray drier 20 wherein the hydrogel is reduced tomicrospherical form, the pore size set and the hydrogel converted toessentially boehmite; a muller 30 wherein water is added to themicrospherical boehmite to physically convert the latter to a paste ofextrudable consistency; and, an extruder 40 wherein the granulatedboehmite is extruded through an aperture or die. If it is desired toform spheres (which are formed from extrudates), the extrudates arefirst dried in extrudate drier 50 and then passed through a series ofmarumerizers 60, 70 wherein the extrudates are broken, fragmented andformed into spheres. If extrudate forms are desired, the granulatedmaterial from the extruder 40 can be passed directly to the extractor80, or dried in extrudate drier 50 and then passed to the extractor 80.Suitably, extrudates from drier 50, or spheres from the marumerizers 60,70, are passed to extractor 80, wherein the polymer is separated fromthe extrudates or spheres, and the solvent and polymer are recovered. Inthe extraction of the solvent and polymer, the extrudates from drier 50,or spheres from the series of marumerizers 60, 70, are initiallycontacted with fresh or recycle solvent from the stripping column 90,and the used solvent and shaped boehmite then separated one from theother. The used solvent is then passed to distillation column 100wherein polymer is recovered from the bottom of the column and recycledto the blender 10. Overhead from the distillation column 100,principally solvent and water are then passed to stripper 90 whereinsolvent is removed from the stripper 90 and passed to the extractor 80,and water is also rejected from the stripper. (In some instances it mayalso be desirable to extract polymer from the dried solids prior to theformation of spheres or extrudates. In such case the product fromblender 10 is dried in spray drier 20, or a low temperature drier. Thedried product is then contacted in extractor 80, and the extractedproduct recycled to muller 30 for treatment in the sequence of stepsdescribed. Product from the marumerizer 70 would then be dried, anddirected to calciner 110.) The recovered granulated boehmite solids fromextractor 80 are passed to a first calciner 110 wherein the boehmite isconverted to gamma alumina. Gamma alumina from calciner 110, in the morepreferred embodiment, is then impregnated in impregnation stage 120,with the desired Group VIB or Group VIII metal, or preferably anadmixture of Group VIB and Group VIII metals, dried in drier 130, andthen again calcined in the second calciner 140, from where the finishedcatalyst is removed.

The polymer is added to the hydrogel in polymer solvent blender 10.Within blender 10, a solution of the desired water soluble polymer isblended with sufficient of a recycle stream from the distillation column100 to displace water and add polymer to the alumina hydrogel inpolymer:alumina ratios ranging from about 0.5:1 to about 4:1, preferablyfrom about 1:1 to about 2:1, based on weight, at generally ambienttemperature and pressure, suitably at temperatures ranging from about70° F. to about 85° F. Makeup polymer can be added, if required. Thehydrogel is removed from the blender 10 as a slurry, suitably a pumpableslurry and, if necessary, excess water-polymer solution or water isadded for such purpose.

Spray drier 20 is employed to convert the hydrogel to boehmite, and formthe pore structure required for good hydrodesulfurization anddemetallization properties. Suitably, the hydrogel is spray dried, i.e.,dried by countercurrent contact of an atomized hydrogel spray with air,at air temperatures ranging from about 250° F. to about 350° F., andpreferably at temperatures ranging from about 275° F. to about 300° F.Relatively low temperatures are desirable to minimize oxidation, and toavoid decomposition and loss of polymer. The temperature of the hydrogelor boehmite per se is maintained below about 250° F., and preferablyfrom about 225° F. to about 250° F. Pressures are not critical, andgenerally atmospheric or near atmospheric pressure is employed. Thespray drier per se is conventional, nozzles of various commercial typesbeing suitable for ejection of the hydrogel slurry as a spray. On egressof the granulated boehmite from the spray drier 20 the microsphericalsolids range in average particle size diameter from about 75 to about125 microns. Generally, the spray drier material contains from about 30to about 35 weight percent alumina, from about 30 to about 60 weightpercent polymer, and from about 5 to about 40 weight percent water.

The muller 30 is used to adjust the solids content of the alumina toassure a paste of extrudable consistency. At this point, e.g., if toomuch water has been removed in the drying step, a liquid, suitablywater, can be added to form an extrudable homogeneous paste. The solidscontent of the paste leaving the muller 30 is critical, and hence theamount of water added, if any, is somewhat critical. If, on the onehand, too much water is added, it is impractical to extrude the materialbecause it becomes too sticky, and beyond this point it becomesimpossible to form an extrudable solids phase. On the other hand, if toolittle water is present, the material cannot be extruded withoutsignificant loss of pore volume, and degradation of the pore sizedistribution. To avoid excessive pore volume loss, it is desired tomaintain >20 weight percent solids, preferably >22 weight percentsolids, albeit added water facilitates the expression of the pastethrough the die apertures. Torque has been found to increaseexponentially as the solids content of the paste is increased aboveabout 25 weight percent, and this also tends to decrease pore volume.For this reason it has heretofore been considered undesirable to extrudealuminas of solids contents greater than 30 weight percent.

In application Ser. Nos. 646,490 - 646,492, supra, extrusion by theapplication of high torques was avoided, not merely because greaterenergy was required, but principally because some of the desired porestructure created at much effort was lost. The torques that were appliedwere below 25 inch-pounds, and the solids contents of the pastes weremaintained below about 30 weight percent. It has now been discovered,however, that higher torques can be applied to great advantage albeitsome of the desired pore structure is crushed and lost. By use oftorques ranging from about 25 to about 55 inch pounds, preferably fromabout 40 to about 50 inch pounds it has been discovered that macroporevolume, i.e., pores of sizes ranging 400A+, particularly 1000A+, can bedrastically reduced. In accordance with this invention macropore volumein 400A+ pores has been further reduced by the application of suchtorques to 0.2 cc/g, and preferably below 0.1 cc/g, which has anenhanced effect in improving the activity maintenance of the catalyst.Further, even where some of the catalyst activity is lost as a result ofloss of pore structure in the desired ranges, even this can be off set,or compensated for by improved impregnation techniques subsequentlydiscussed in detail. For best results in the macropore volume reduction,the solids content of the paste is maintained between about 26 and 32weight percent, preferably between about 29 and 32 weight percentsolids.

The solids content of the paste is regulated within the muller 30 forreasons stated, but to some degree the solids content is regulated toproduce the desired particle size of the spheres, where spheres aredesired. In general, the relation between the solids content of thepaste, the required extrudate diameter, and the average sphericalparticle size diameter within the range of torques expressed is asfollows:

    ______________________________________                                        Solids Content                                                                            Required Extrudate,                                                                         Average Sphere Size                                 of the Paste, Wt. %                                                                       Diameter, Inches                                                                            Diameter, Inches                                    ______________________________________                                        30-32       1/55-1/28     1/50-1/25                                           28-30       1/32-1/21     1/25-1/16                                           26-28       1/24-1/12     1/16-1/8                                            ______________________________________                                    

The paste from the muller 30, containing the desired amount of solids,is conveyed as a substantially homogeneous mass to the extruder 40 forformation of the paste into extrudates. In forming extrudates, theboehmite paste is extruded through a die, suitably one having aplurality of apertures to form "spaghetti," or spaghetti-like shapes.The spaghetti-like shapes can be sized to the desired length by cuttingthe shapes as they are emitted from the mouth of the extruder, or brokenand sized downstream of the extruder by conventional means; even bynormal breakage as occurs, e.g., when such material is conveyed on beltdriers. Excessive torque is to be avoided in the extrusion, consistentwith the objectives stated, to avoid loss of pore volume and degradationof the pore size distribution by distortion or crushing of the pores inthe desired ranges. The smaller the die apertures, of course, thegreater the force required to effect the extrusion and, whereas thereduction of the solids content of the paste (by water addition at themuller 30) lessens the amount of force that must be applied, there is,as stated, a limit on the amount of water than can be added (or solidsreduced) because excessive water also causes loss of pore volume andpore size distribution during extrusion as well as loss of crushstrength. In general, with conventional extrusion equipment, e.g, a lowtorque extruder, Model 0.810 Research Extruder manufactured by WeldingEngineers of King of Prussia, Pennsylvania, extrudates of outstandingquality of cross-sectional diameters ranging from about 1/40 to 1/16inch have been produced.

The cross-sectional diameter of the extrudate is preselected to providean extrudate of the desired diameter, or the desired sphere sizes, asphere being of somewhat larger particle size diameter, generally fromabout 10 percent to about 50 percent larger than the diameter of theextrudate from which it is produced. The difference between spherediameter and extrudate diameter is primarily dependent upon the weightpercent solids of the paste from which the extrudate is formed, whichrelationship will be better understood by a consideration of themechanism involved in the formation of spheres from extrudates discussedin Application Ser. Nos. 646,490 - 646,492, herewith referred to andincorporated by reference.

Extrudates are next dried in drier 50, suitably a circulating air oven,at temperature ranging from about 150° F. at residence time sufficientto form extrudates of critical solids content above about 20 weightpercent, suitably within a range of from about 22 to about 32 weightpercent, preferably within a range of from about 26 to about 32 weightpercent, and more preferably from about 29 to about 32 weight percent.

In the formation of spheres, where spheres are the desired catalystform, the extrudates, of critical solids content, are next fed batchwiseor continuously, preferably the latter, to a series of two or moremarumerizers 60, 70. The first marumerizer 60 of the series is providedwith a rotatable roughened plate suitably of grid design for breaking upthe extrudates which initially form into "dumbbell" shapes, whichgradually and progressively separate into spheres, and the secondmarumerizer 70 is provided with a smooth rotatable plate for smoothingthe surfaces of the preformed spheres. Suitable marumerizers for suchpurpose are available commercially, e.g., a Q-230 model made by EliLily. A suitable grid is one described as 1.5 mm. friction plate asdescribed in the Marumerizer and Extruding Equipment Operating Manualpublished by Equipment Sales Dept., Elanco Products Co. of Indianpolis,Indiana, and a suitable smooth plate is one characterized as a polishingplate described in the same publication.

In the operation of marumerizers 60, 70, dry spaghetti-like extrudatesare dropped onto the revolving grid plate of marumerizer 60, and after asuitable residence time the spheres are passed into marumerizer 70, tofinish the formation of the spheres. The time required formarumerization is a direct function of the solids content of theextrudate, the speed of rotation of the plates of the marumerizers 60,70 and type of plates used. Typically, the time required formarumerization ranges from about 10 minutes to about one-half hour.Initially, a single fragment of an extrudate is broken into a pluralityof segments having length: diameter ratios ranging from about 8:1 toabout 10:1. Within, e.g., about 15 seconds a first dumbbell shape isformed from a segment, and after about 30 seconds one or more of theends of the dumbbell are broken off and formed into spheres. The processis continued until finally a short dumbbell segment or double sphere, isformed into a single sphere which generally occurs within from about 2to about 5 minutes. Generally, from about 6 to about 8 spheres areformed from an original extrudate segment. The spheres are somewhatirregular in shape when contacted with the plate of marumerizer 60, butare rounded off to become smooth, uniform spheres in marumerizer 70where they are buffed upon the smooth plate. The size of the spheresformed is a function of the extrudate diameter and the weight percentsolids.

The spheres, or extrudates, e.g., from drier 50 (where the extrudatecatalyst form is desired), are contacted in the extraction zone, orextractor 80, with fresh solvent to extract the polymer. The extractioncan be done batchwise or continuously, preferably continuously.Extraction is suitably accomplished in a preferred embodiment by use ofa moving bed extractor wherein the solids are introduced into the top ofa column, and hot solvent is introduced into the bottom of the column.Suitably, the fresh solvent is introduced at temperature ranging fromabout 140° F. to about 285° F., or preferably from about 175° F. toabout 230° F. Preferably, the solvent is introduced at a temperaturejust below, or at its boiling point. Hot solvent is removed from the topof the column, and the extracted boehmite solids are removed from thebottom of the column.

The polymer containing solvent, as schematically depicted in the figure,is passed into a distillation column 100, a polymer or polymerconcentrate being separated and removed from the bottom of the column100 and recycled to the blender 10. A solvent and water mixture, takenfrom the overhead of column 100, is passed to a stripper 90 for removalof water, and the dehydrated polymer-denuded solvent is recycled toextractor 80.

Various solvents are suitable for the extraction of the polymer andwater from the boehmite spheres, or extrudates. The solvent employed isone which is soluble in water, and which is capable of dissolving thepolymer from the spheres. It is also desirable that the solvent be onewhich can be desiccated, or one from which the water can be easilystripped. Suitably, also, it is one which boils within a range of fromabout 140° F to about 315° F, preferably from about 175° F to about 315°F. Low molecular weight alcohols are a particularly preferred class ofsolvents, preferably those which contain from 1 to about 6 carbon atoms,more preferably from about 4 to about 6 carbon atoms, in the totalmolecule. The monohydric alcohols are preferred. Other solvents whichmay be employed are ethers, aldehydes, ketones, halogenatedhydrocarbons, e.g., chlorinated hydrocarbons, and the like, generallywithin about the same molecular weight range as the alcohols. Inextraction with the low molecular weight alcohols, e.g., methanol,ethanol, isopropanol, n-propanol, 1-butanol, amyl alcohol, hexanol andthe like, generally from about 70 to about 95 weight percent of thepolymer is recovered.

The spheres, or extrudates, on egress from the extractor 80 are dried toremove the solvent, suitably at ambient temperatures or at temperaturesranging from about 100° F to about 600° F, preferably from about 300° Fto about 500° F. Suitably, the spheres, or extrudates, are dried incirculating air, in vacuum, microwave oven, or the like, at least for atime sufficient to remove liquid from the pores.

The dried spheres, or extrudates, are then calcined as in a firstcalciner 110 to convert the boehmite to gamma alumina. In thecalcination, it is required to raise the temperature of the driedspheres to at least about 1000° F in an atmosphere of nitrogen or othernonreactive medium, but preferably the calcination is conducted in anatmosphere of air. If air is not employed initially, then a terminalstep must be employed wherein the catalyst is heated in air at atemperature of at least about 1000° F., preferably from about 1200° F.to about 1400° F. It is found that gamma alumina is readily formed byraising the temperature from ambient to about 1000° F., or higher, at arate in excess of about 2° F./minute, preferably from about 3° F./minuteto about 5° F./minute. After calcination temperature is reached, thetemperature is maintained for periods ranging from about 10 minutes toabout 6 hours, from about 2 to about 4 hours being typical, preferablythe alumina being calcined in air for the entire period.

Preferably, in the practice of this invention, a metal hydrogenationcomponent, or components, is added to the gamma alumina sphere, orextrudate, by impregnation rather than by hydrogel impregnation aspreviously discussed. In such impregnation, the calcined gamma aluminais thus next composited with a metal hydrogenation component, orcomponents, e.g., as by impregnation within an impregnation stage 120,or series of such stages. The Group VIB and Group VIII metal components,admixed one component with the other or with a third or greater numberof metal components, can be composited or intimately associated with theporous inorganic oxide support or carrier in impregnation zone 120 byimpregnation of the support with the metals, e.g., with the alumina, byan "incipient wetness" technique, or technique wherein a metal, ormetals, is contained in a solution, preferably alcohol, in measuredamount and the entire solution absorbed into the support andsubsequently dried and calcined to form the catalyst.

In forming a solution for impregnation of a support, the necessaryamount of solution to be employed in such recipe (measured in cubiccentimeters, cc) for impregnation of a support by an incipient wetnesstechnique can be determined quite closely by multiplying the pore volume(PV) of the support to be impregnated by the weight of the support,which product is then multiplied by a factor of 1.6. A more preferredmethod of impregnation, however, requires about three times the volumeof solution as required for impregnation by the incipient wetnesstechnique. By a threefold increase in the volume of solution used forthe impregnation, more time is allowed for the diffusion of the metalsinto the pores. In a particularly preferred embodiment, the metal, ormetals, is added to the catalyst in small dosages by incrementaladditions of the solution. In this mode of catalyst preparation, themetal, or metals, is more uniformly deposited and deeper penetration ofthe pores by the metal, or metals, is effected. Better dispersion of themetals throughout the catalyst is obtained, and there is far less"capping off" or closure of the pores by metal deposits formed at poreentrances.

The method of drying the catalyst to remove the solution from thecatalyst constitutes a key and novel feature of the present invention,and produces a considerable improvement in the activity of the catalystfor hydrodesulfurization. The drying step in all its aspects is carriedout, as in drier 130, by a controlled slow rate of evaporation of thesolvent from the catalyst, suitably at a rate less than about 2°F./minute, and preferably at a rate not exceeding about 1° F./minute.The metal, or metals, impregnated catalyst, while yet wet, butpreferably surface dried, is heated at such slow rate up to a minimumtemperature corresponding to the boiling point of the solvent containedwithin the catalyst, and preferably to a temperature ranging up to about50° F., suitably from about 25° F. to about 50° F. above the boilingpoint of said solvent. Partial saturation of the vapor space above thecatalyst with a solvent identical to that being evaporated constitutes apreferred technique for controlling the rate of evaporation of thesolvent from the pores of the catalyst, this being particularlydesirable for relatively low boiling point liquids, e.g., water and C₁to C₃ solvents, e.g., alcohols.

In one of its aspects, e.g., a surface dry catalyst having beenimpregnated with an aqueous or C₁ -C₃ metals-containing solution isplaced in a circulating oven, rotary drum drier or the like, at ambientor room temperature, and a non-reactive or inert sweep gas is passedthereover while the temperature of the catalyst is increased at a rateless than about 2° F./minute, preferably less than about 1° F./minute.Suitably, to aid in controlling the rate of evaporation of moisture fromthe pores of the catalyst, the entering sweep gas is one saturated withat least about 5 percent, preferably at least about 15 percent, and morepreferably at least about 25 percent, based on the total volume of thegas, of water or of the respective C₁ -C₃ alcohol being evaporated fromthe catalyst. Whereas almost complete saturation of the sweep gas withthe respective C₁ -C₃ alcohol produces satisfactory results, and slowsthe rate of evaporation, this is not necessarily economical becauserecovery of the alcohol is generally desirable and hence oversaturationof the gas may unduly burden the process.

In another of its aspects, the rate of evaporation can be more readilycontrolled by use of a higher boiling solvent, e.g., a C₄ -C₆ alcohol,(1) by the use of such solvent in the initial metal, or metals,impregnation or (2) by immersing the water of C₁ -C₃ containing metal,or metals, impregnated into the higher molecular weight alcohol solutionand permitting equilibration and displacement of the lower boilingsolvent from the pores of the catalyst. Suitably, this can beaccomplished by immersion of the surface dried catalyst containing thelow molecular weight solvent into a bath of the higher molecular weightsolvent, at room temperature or at elevated temperature and allowingsufficient time for equilibration. Preferably, the bath is heated to theboiling point of the high molecular weight solvent, and the boilingcontinued for a period ranging from about 2 to about 6 hours after whichtime the lower boiling solvent have been virtually completely displacedby the higher boiling solvent. Whereas the vapor space above thecatalyst can be partially saturated to control the rate of evaporationof solvent from the pores, this is not generally necessary with thehigher boiling solvents.

The reason for the increased hydroconversion activity of catalystsprepared by such slow drying technique vis-a-vis catalystsconventionally prepared without regard to drying rate is not understood,though Applicant believes that this phenomenon is subject to areasonable explanation. Applicant believes that the slow dryingtechnique produces a gradual and more controlled and gradual salting outof the metal, or metals, from solution as the meniscus of liquid recedeswithin the capillary pores and openings within the catalyst. On the onehand, a fast drying rate favors deposition of relatively largeagglomerates of metal at or near the mouths of the pores. Not only arethe pore mouths blocked by these deposits, but also only a relativelysmall amount of metal, if any, is deposited deep within the pores. Theexits, or pore mouths, thus tend to be restricted by such unfavorabledeposition of the metals and diffusion of reactants into the poresbecomes more difficult. Also, there are fewer active sites because themetal is not adequately dispersed. On the other hand, slow drying ratesfavor a very gradual salting out or dispersal of the metals within thepores, with the consequence that the deposits are of much smaller size,more uniform and extend far deeper into the pores. The latter catalystsare thus considerably more active because the reactants and reactionproducts can better diffuse into and out of the pores of the individualcatalyst particles, and there are far more active sites available tocatalyze the reaction. Consequently, any of the catalysts heretoforedescribed and others can be improved by this method of drying. Evenoff-specification catalysts can be improved by this method ofimpregnation and drying.

After the catalyst has been dried sufficient to complete the metalsdeposition, the temperature may then be elevated sufficiently to assumethat all of the alcohol has been removed from the catalyst, e.g., byelevating the temperature to about 500° F. The catalyst is then againcalcined as in Calciner 140. Suitably, the calcination is conducted attemperatures ranging above about 900° F., preferably from about 1000° F.to about 1100° F. in air. The catalysts thus formed are particularlysuitable for use in hydroconversion processes as fixed beds andebullating beds, but can be used in slurry form. When used in the formof fixed beds, the particle size diameter of the catalysts generallyranges from about 1/32 to about 1/8 inch, preferably about 1/16 inch.When used as ebullating beds, the catalyst generally range about 1/32inch diameter and smaller.

The finished catalyst is comprised of a composite of a refractoryinorganic support material, preferably a porous inorganic oxide supportwith a metal or compound of a metal, or metals, selected from Group VIBor Group VIII, or both, the metals generally existing as oxides,sulfides, reduced forms of the metal or as mixtures of these and otherforms. Suitably, the composition of the catalysts comprises from about 5to about 50 percent, preferably from about 15 to about 25 percent (asthe oxide) of the Group VIB metal, and from about 1 to about 12 percent,preferably from about 4 to about 8 percent (as the oxide) of the GroupVIII metal, based on the total weight (dry basis) of the composition.The preferred active metallic components, and forms thereof, comprise anoxide or sulfide of molybdenum and tungsten of Group VIB, an oxide orsulfide of nickel or cobalt of Group VIII, preferably a mixture of oneof said Group VIB and one of said Group VIII metals, admixed one withthe other and inclusive of third metal components of Groups VIB, VIIIand other metals.

Preferred catalysts are constituted of an admixture of cobalt andmolybdenum, but in some cases the preferred catalysts may be comprisedof nickel and molybdenum. The nickel-molybdenum catalyst possesses veryhigh hydrogenation activity and is particularly effective in reducingCon carbon. Other suitable Group VIB and VIII metals include, forexample, chromium, platinum, palladium, iridium, osmium, ruthenium,rhodium, and the like. The inorganic oxide support is preferablystabilized with silica in concentration ranging from about 0.1 to about20 percent, preferably from about 10 to about 20 percent, based on thetotal weight (dry basis) alumina-silica composition (inclusive of metalcomponents).

Particularly preferred catalysts are composites of nickel or cobaltoxide with molybdenum, used in the following approximate proportions:from about 1 to about 12 weight percent, preferably from about 4 toabout 8 weight percent of nickel or cobalt oxide; and from about 5 toabout 50 weight percent, preferably from about 15 to about 25 weightpercent of molybdenum oxide on a suitable alumina support. Aparticularly preferred support comprises alumina containing from about10 to about 20 percent silica. The catalyst is sulfided to form the mostactive species. The bulk density of the catalyst generally ranges fromabout 0.2 to about 0.6 g/cc, preferably from about 0.2 to about 0.5g/cc, depending on particle size.

The invention will be more fully understood by reference to thefollowing selected nonlimiting examples and comparative data whichillustrate its more salient features. All parts are given in terms ofweight units except as otherwise specified.

In certain of the examples, and illustrations hereinafter described, thehydrodesulfurization and demetallization activity of the catalysts ofthis invention are compared with prior art catalysts, particularlycatalysts made by the ethylene oxide process and by the earlier polymerextension method disclosed in the applications of Sawyer et al. andRobson, supra.

For purposes of comparison, Catalyst "EOC" has been taken as thestandard ethylene oxide catalyst since its hydrodesulfurization anddemetallization activities are unsurpassed among the catalysts whichhave been heretofore produced by the ethylene oxide method, and hencethis catalyst has been assigned a hydrodesulfurization activity of 100,and a demetallization activity of 100. The properties of the StandardEOC Catalyst are given in Table I as follows:

                  TABLE I                                                         ______________________________________                                        STANDARD ETHYLENE OXIDE CATALYST                                              Surface Area .sup.(1)                                                                              359                                                      Pore Volume .sup.(2), cc/gm                                                                        1.38                                                     Pore Volume .sup.(3), cc/gm                                                                        1.48                                                     PSD PV in .sup.(4)                                                            0-50A                0                                                        150-250A             32.4                                                     350A+                11.0                                                     PSD, cc/gm PV in .sup.(5)                                                     100-200A             0.70                                                     200-400A             0.29                                                      400A+               0.24                                                     1000A+               0.05                                                     Metals Content, Wt. %                                                         CoO                   6.0                                                     MoO.sub.3            20.0                                                     ______________________________________                                         .sup.(1) Single Pt. BET.                                                      .sup.(2) Single Pt. N.sub.2 adsorption filling pores.                         .sup.(3) Digisorb desorption total PV.                                        .sup.(4) Adsorptomat.                                                         .sup.(5) Combination Digisorb desorption and Hg intrusion.               

Hydrodesulfurization and demetallization activities can best be comparedin actual crude hydroconversion reactions and, for this purpose, a ColdLake petroleum crude was employed as a standard feed in most of theexamples and data hereinafter presented. The Cold Lake petroleum crudeused for this purpose is identified as follows:

                  TABLE II                                                        ______________________________________                                        STANDARD FEED                                                                 FEEDSTOCK INSPECTIONS                                                         Inspections                                                                   Gravity, ° API                                                                              11.1                                                     Sulfur, Wt. %        4.5                                                      Nitrogen, Wt. %      0.459                                                    Oxygen, Wt. %        0.2                                                      Con. Carbon, Wt. %   12.0                                                     Asphaltenes (C.sub.5), Wt. %                                                                       17.9                                                     Carbon, Wt. %        83.99                                                    Hydrogen, Wt. %      10.51                                                    Metals ppm                                                                     Ni                  74                                                        V                   180                                                       Na                  18                                                        Solids (3 Micron-filter)                                                                          92                                                       VSU at 210° F.                                                         D-1160                                                                        IBO                  463                                                      5                    565                                                      10                   622                                                      20                   712                                                      30                   817                                                      40                   916                                                      50                   1019                                                     % Rec.               56.4                                                     % Res.               42.4                                                     Light Ends            1.2                                                     ______________________________________                                    

In Examples 1 and 2, immediately following, the preparation of apolyethylene glycol (PEG) alumina extrudate under generally optimumconditions is described, such extrudate being impregnated with ahydrogenation component to provide a catalyst having well balancedhydrodesulfurization and demetallization properties.

EXAMPLE 1

An alumina hydrogel was prepared by combining a first solution, i.e., asodium aluminate solution, and a second solution, i.e., an aluminumsulfate solution, at 50° F. In the preparation of the first solution, asodium aluminate slurry was prepared by mixing 25.7 kg of NaOH with 24.9kg of aluminum trihydrate. The slurry was then cooled, diluted with1260.1 kg of water, and 2.3 kg of tetraethylorthosilicate then added tothe aluminum sulfate solution. In the preparation of the secondsolution, approximately 75.6 kg of aluminum sulfate was dissolved in629.7 kg of deionized H₂ O, and the solution filtered. The filteredaluminum sulfate solution was then added slowly to the sodium aluminateslurry at 50° F, and the addition continued to a pH of 10. The slurrywas then heated to 120° F. and filtered to recover the gel. The gel wasslurried with deionized water and washed until the Na₂ O content of thegel was less than 0.1 Wt.%, and SO₄ less than 1.5 Wt.%.

The washed gel was then mixed with 48.4 kg of polyethylene glycol (ca. 2weights of PEG/1 weight of Al₂ O₃) and reslurried with water to providea slurry containing 5-10 Wt.% solids in liquid. The slurry was thenspray dried, the feed rate of the burner having been adjusted tomaintain a spray drier bottom temperature of 300°-350° F. The producthad a particle size range of approximately 50-150 microns (0.002-0.006inch particle size diameter) and a solids (Al₂ O₃) content of ca. 35Wt.%.

A 6500 gm portion of the spray dried alumina was then divided and mulledin 500 gm batches using a Cincinnati muller, which is the equivalent tomulling with a commercial muller or extrusion through a die having3/16-inch holes. To each 500 gm batch, 90 cc of water and 8 drops ofacetic acid were added prior to mulling. The acid acts as an extrusionaid by peptizing the alumina. The mulled material was extruded through a3-hole 1/16-inch drill, non-recessed die at 1000 RPM applying 45-50in.-lbs. of torque. The extrudates were air dried for 15 minutes,extracted in isopropyl alcohol for 1 hour at 160° F, and then extractedin hexanol for 1 hour at 260° F to remove the polymer. The extrudateswere then calcined 1 hour at 500° F in N₂, 2 hours at 1000° F in N₂, and2 hours at 1000° F in air. The properties of these extrudates are givenin Table III, at Column 2, below. By controlling the torque in the 30-55in.-lbs. region, but particularly in the 45-50 in.-lbs. range, a blankextrudate having highly desirable porosity properties can thus beobtained. The extrudate, it will be noted, also had good crush strength,the 4.8 lbs. crush strength having been determined by using the standard1/8-inch anvil test.

EXAMPLE 2 (Catalyst 1E-21031)

This examples shows that by properly impregnating and drying a materialsuch as that described in the foregoing example, a highly desirablecatalyst with balanced hydrodesulfurization and demetallizationproperties can be prepared, one that is fully equivalent to an ethyleneoxide catalyst.

2285 grams of alumina, prepared as per Example 1, was thus impregnatedby first air-exposing to equilibrate with the moisture of the air. Thealumina was then placed in 9000 cc of methanol to which was added 158grams of cobalt chloride. The alumina was maintained in this solutionfor 1 hour and allowed to equilibrate. Two additional similar incrementsof 158 gm of cobalt chloride portions were then added to the methanol,one hour being allowed between each incremental addition. Next, 179grams of phosphomolybdic acid were added to the methanol and the aluminamaintained in this solution for 1 hour. Thereafter, three additionalsimilar increments of phosphomolybdic acid were added to the solution,and the catalyst allowed to equilibrate for one hour after eachaddition. The solution was then allowed to stand for 17 hours, afterwhich time the methanol was evaporated at 120° F until no surfacemethanol remained. The catalyst, which contained 5% CoO and 18% MoO₃,was simmered in hexanol for 1 hour at 260° F to displace methanol fromthe pores. The catalyst was then calcined at 500° F for 1 hour in N₂,next at 1000° F for 2 hours in N₂, and then at 1000° F for 2 hours inair. The properties of the catalyst are given in Table III, at Column 3,which follows:

                  TABLE III                                                       ______________________________________                                                       Extrudate  Catalyst                                                           of Example 1                                                                             IE-21031                                            ______________________________________                                        Surface Area .sup.(1), m.sup. 2/gm                                                             375          269                                             Pore Volume .sup.(2), cc/gm                                                                    1.13         0.80                                            Pore Volume .sup.(3), cc/gm                                                                    1.22         0.85                                            PSD, cc/gm PV in .sup.(4)                                                     100-200A         0.56         0.40                                            200-400A         0.12         0.09                                             400A+           0.06         0.03                                            1000A+           0.03         0.03                                            Strength, lbs.   4.8          --                                              ______________________________________                                         .sup.(1) Single Pt. BET.                                                      .sup.(2) Single Pt. N.sub.2 adsorption filling pores.                         .sup.(3) Digisorb desorption total PV.                                        .sup.(4) Combination Digisorb desorption and Hg intrusion.               

Side-by-side runs were made with Cold Lake petroleum crude,characterized in Table I, preheated to reaction temperature, andconcurrently fed, with hydrogen, at the same temperature, downwardlythrough each of a pair of reactors, each containing a fixed bed ofsulfided EOC Standard Catalyst (Table I) and Catalyst IE-21031,respectively. The process was run at a temperature of 750° F and under apressure of 2250 psig. The feed rate was maintained at 1 V/V/Hr.,hydrogen was fed at a rate of 6000 SCF/Bbl., and the runs were conductedover a period of 9 days. The results obtained are given as follows:

    ______________________________________                                                        Standard                                                                      Ethylene Oxide                                                                              Catalyst                                        Catalyst        Catalyst      IF-21031                                        ______________________________________                                        Relative Activity                                                             after 9 Days                                                                  Hydrodesulfurization                                                                          100           109                                             Vanadium Removal                                                                              100           100                                             ______________________________________                                    

The IE-21031 catalyst was thus equal or superior to the standardethylene oxide catalyst for hydrodesulfurization and demetallization.

These data show that Catalyst IE-21031 has the desired low macroporosityin both the 400A+ and 1000A+ pores which provides goodhydrodesulfurization activity maintenance; 100-200A pores which providesgood hydrodesulfurization activity; and 200-400A pores which providesgood demetallization. The low macroporosity excludes some of the verylarge metals-containing molecules from the pores of the catalyst, andhence excessive amounts of such metals are not deposited therein, thisbeing necessary to insure good hydrodesulfurization activitymaintenance.

In considering the properties of the Standard ethylene oxide, or EOC,Catalyst (Table I), one observes that the 1000A+ macroporosity isreasonably low, but the 400A+ macroporosity is excessive. Yet theethylene oxide catalysts, in the light of the data which led to thepresent discovery, have relatively good activity maintenance; betterthan would be expected in the light of what is now known about thepolymer-extended catalysts. The ethylene oxide catalysts, unlike thepolymer-extended catalysts, tolerate excessive macroporosity in the400A+ pores. Apparently, this is because the ethylene oxide catalystshave relatively greater surface areas, and consequently greater numbersof active sites. However, the polymer-extended catalysts, albeit theyhave relatively fewer active sites, do have sites which are more active,and thus such catalysts do possess higher extrinsic activity.Consequently because there are more active sites on the ethylene oxidecatalysts, they can tolerate poisons more effectively than thepolymer-extended catalysts. The sites of the polymer-extended catalystsbeing more active must be protected from the poisoning effect of thelarge molecules by minimizing the 400A+ macropores.

The superior intrinsic activity of the active sites of thepolymer-extended catalysts of this invention for purposes ofhydrodesulfurization is demonstrated by the following test data.

EXAMPLE 3

For comparative purposes, both the Standard EOC ethylene oxide catalystand Catalyst IE-21031 of Example 2 were tested for hydrodesulfurizationactivity using a standard vacuum gas oil, the inspections on which arepresented in Table IV as follows:

                  TABLE IV                                                        ______________________________________                                        VACUUM GAS OIL                                                                FEEDSTOCK INSPECTIONS                                                         Inspections                                                                   Gravity, °API                                                                          21.2                                                          Sulfur, Wt. %   2.37                                                          Nitrogen, Wt. % 0.090                                                         Metals, ppm                                                                    Ni             0.11                                                           V              0.68                                                          D-1160                                                                        IBP             603                                                           5               786                                                           10              822                                                           50              909                                                           95              991                                                           Dry             1050                                                          ______________________________________                                    

Runs were made with the feed, characterized in Table IV, preheated toreaction temperature and concurrently fed, with hydrogen, at the sametemperature, upwardly through a reactor. In each run, the reactorcontained a fixed bed of sulfided EOC Standard Catalyst (Table I) andCatalyst IE-21031 (Table III), respectively. The run in each instancewas conducted at a temperature of 670° F and under a pressure of 1500psig, while the feed rate was maintained at 0.5 V/V/Hr., and hydrogenwas fed at a rate of 1500 SCF/Bbl. The runs were conducted over a periodof 4-6 days, the results obtained being given as follows:

    ______________________________________                                                        Standard                                                                      Ethylene Oxide                                                                              Catalyst                                        Catalyst        Catalyst      IE-21031                                        ______________________________________                                        Relative Activity                                                             after 6 Days                                                                  Hydrodesulfurization                                                                          100           140                                             ______________________________________                                    

The sulfur bearing molecules of the feed are sufficiently small thatdiffusion limitations are minimized. Thus, the hydrodesulfurizationactivity measured in this manner is a measure of the basic intrinsicactivity of the hydrodesulfurization sites. These data show that theimproved polymer extended catalyst was about 40% more active than thestandard EOC ethylene oxide catalyst. It is believed that the improvedpolymer extended catalyst has fewer active sites because of the lowersurface area of the catalyst, but the intrinsic activity of these sitesis considerably higher than those of the standard EOC ethylene oxidecatalysts. Thus, the sites have to be protected from the poisoningeffect of the very large molecules by low 400A+ macroporosity, thispreventing access and adsorption of the very large molecules within thepores of the catalyst. Albeit the standard EOC ethylene oxide catalystprobably has more sites by virtue of its higher surface area, the sitesare probably less active than those of Catalyst IE-21031. Consequently,a higher level of macroporosity is tolerated in the standard EOCcatalyst as contrasted with the polymer-extended catalyst.

The following example is exemplary of conditions employed in theextrusion of various extrudates to provide alumina shapes of desirableporosity, particularly as relates to the application of torque.

EXAMPLE 4

a. Sample EB-10353, characterized in Table V, Column 2, is constitutedof spray-dried PEG alumina extrudates prepared pursuant to the methoddisclosed in the Sawyer et al and Robson applications. The preparationof this material is described as follows: 6220 grams of the spray driedalumina prepared in Example 1 was mixed with 2520 cc of water to providea 25% solids content. After initial mulling with mortar and pestle, thematerial was extruded through a 3/16-inch drill die containing 3 holesand having a 5/8 -inch land length at 200 RPM, using the WeldingEngineer 0.810 extruder. A torque of 10 in.-lbs. was applied, thismulling the material in a manner comparable to a commercial muller. Thismaterial was then extruded through a recessed face die containingtwenty-three #72 drill holes and a land length of 5/8-inch byapplication of 23 in.-lbs. of torque. The extrudates were dried from 25to 27% solids, and the material then successively extracted inisopropanol for 1 hour at 180° F, and hexanol for 1 hour at 280° F. Theextracted extrudates were then calcined at 1000° F for 2 hours in N₂,and then for 2 hours in air. The properties of the material are given inTable V, at Column 2.

b. Sample MB-10361, the properties of which are described in Table V,Column 3, is constituted of spray-dried PEG alumina spheres made fromextrudates, both the spheres and extrudates also having been preparedpursuant to the method disclosed in the Sawyer et and Robsonapplications. The preparation of this material is described as follows:6620 gms of the spray-dried PEG powder mentioned in Example 4 (a),supra, was mixed with 2520 cc of H₂ O to make a paste containing 25%solids, and this material was mulled in identical manner. Then, themulled paste was extruded as in Example 4 (a), this time by applicationof a torque of 22 in.-lbs. The extrudates were then dried to 27% solidsand marumerized at 970 RPM on the coarse plate for 22 minutes and on thesmooth plate for 3 minutes. Following this, the spheres were extractedin isopropyl alcohol for 1 hour at 180° F and then in hexanol for 1 hourat 280° F. The spheres were than calcined at 1000° F for 2 hours in N₂,and then for 2 hours in air. The spheres were held at 500° F for 1 hourprior to heating further to 1000° F to insure complete removal of thealcohol before calcining in air at 1000° F, this avoiding possibleburning of the alcohol.

c. Sample 9-A, the properties of which are described in Table V, Column3, was constituted of a 500 gm sample of the spray-dried alumina ofExample 1. To the sample was added sufficient water to make a pastecontaining 28.3% solids. The material was mulled for 45 minutes in aCincinnati muller and then further mulled by extrusion through a 3-hole,3/16-inch drill die. The mulled paste was then extruded through a6-hole, 1/32-inch drill (No. 62 drill) die applying a torque of 30in.-lbs.

d. Sample 9-B, described in Table V, Column 5, was constituted of a 500gram sample of spray-dried alumina of Example 1, and it was also mulledfor 45 minutes in a Cincinnati muller and finally by extrustion througha 3-hole, 3/16-inch drill die which was 5/8 -inch in land length. Waterwas added to the spray-dried solids, originally 35.5% Al₂ O₃, to make apaste containing 30.6% solids. The mulled paste was then extrudedthrough a 1/32-inch die containing 6 holes, yielding a torque of 45-50in.-lbs.

e. Sample 9-C, the properties of which are identified in Table V, Column6, was prepared in a manner identical to that of Sample 9-B except thatthe solids content was 33% solids, and the applied torque was 50-60in.-lbs.

All of these samples were successively extracted with isopropyl alcoholand hexanol, then calcined at 1000° F in N₂ for 2 hours, and then at1000° F in air for 2 hours.

                  TABLE V                                                         ______________________________________                                        Sample       EB-10353 MB-10361  9-A  9-B  9-C                                 ______________________________________                                        Extrusion                                                                     % Solids     25       25        28.3 30.6 33.0                                Torque, in.-lbs.                                                                           23       22        30   45-50                                                                              50-60                               Properties                                                                    Surface Area .sup.(1),                                                                     345      396       443  437  428                                  m.sup.2 /gm-Pore Volume .sup.(2),                                                         1.18     1.09      1.13 1.16 0.97                                 cc/gm                                                                        Pore Volume .sup.(3),                                                                      1.18     1.15      1.22 1.30 1.10                                 cc/gm                                                                        PSD, cc/gm PV .sup.(4) in                                                     100-200A     0.49     0.31      0.31 0.52 0.32                                200-400A     0.6      0.11      0.08 0.11 0.02                                 400A+       0.20     0.20      0.15 0.08 0.02                                1000A+       0.14     0.17      0.14 0.05 0.01                                ______________________________________                                         .sup.(1) As measured by single point adsorption using BET equation.           .sup.(2) Single point nitrogen adsorption obtained by filling of pores.       .sup.(3) Pore volume as measured by Digisorb Desorption test, described       later.                                                                        .sup.(4) Measured by combination of Digisorb Desorption and Mercury           Instrusion.                                                              

In considering these data, it is apparent that the amount of torqueapplied is a critical factor in the preparation of the catalysts of thisinvention. Only the 9-B extrudate, when impregnated and dried bytechniques of this invention, will provide an outstanding catalyst. Thiscatalyst alone has the low macroporosity for good hydrodesulfurizationactivity maintenance, good 100-200A pore volume for highhydrodesulfurization activity, and sufficient of the 200-400A pores forgood demetallization. It is clear from these data that the applicationof too much torque, on the one hand, reduces macroporosity, and also thenumber of 200-400A pores below the level required for gooddemetallization. On the other hand, too little torque does not reducemacroporosity sufficiently for good hydrodesulfurization activitymaintenance. The following example shows the improvement indemetallization and hydrodesulfurization activity which can be obtainedby utilizing the improved impregnation and slow drying techniques. Theperformance of this catalyst is compared to the performance of acatalyst prepared according to the methods disclosed in the applicationof Sawyer et al and Robson, supra.

EXAMPLE 5

A small sample of alumina spheres was prepared in a manner similar tothat described in Example 4(a) (MB-10361). The 1/32-inch alumina sphereshad a surface area of 403 m² /g and a pore volume of 1.19 cc/g. Asolution of 2.5 g of cobalt chloride and 33 g of phosphomolybdic acid in58 cc of methanol was prepared and this solution was poured over 10 g ofthe alumina spheres. The system was allowed to equilibrate for 48 hours.The methanol was evaporated until the surface was essentially free ofliquid methanol. At this time the catalyst was heated to 1000° F in airand held for 2 hours. The catalyst, which was designated IM-20081,represents the application of technology disclosed in Sawyer et al andRobson, supra. This catalyst had a surface area of 289 m² /g and a porevolume of 1.03 cc/g and contained excessive macroporosity similar tothat shown for ample MB-10361 of Example 4.

A second sample of alumina was utilized to make a catalyst. 21 g ofSample EB-10353 was air-exposed overnight to equilibrate with themoisture in the air. The sample was placed in 80 cc of methanol. As inExample 2, the cobalt and molybdenum salts were added incrementally tothe methanol to minimize the formation of large crystallites at the poremouth, and to obtain deeper penetration of the salts into the pores ofthe catalyst. Cobalt nitrate was added in 1.69 g increments over athree-hour period, and phosphomolybdic acid was then added in 1.56 gincrements over a four-hour period. Thus, 5.07 g of cobalt nitrate and6.24 g of phosphomolybdic acid were added to the methanol during thisperiod. The sample was allowed to stand for 17 hours and the sampledried at room temperature until only a small amount of surface methanolremained. Next, the catalyst was heated from room temperature (72° F) to150° F at a rate of 1° F/min. The heatup occurred under a flowing streamof N₂ saturated with methanol at 72° F, or N₂ containing ca. 17%methanol by volume. Once the catalyst bed reached 150° F, it was heldfor 1 hour under the flowing stream of N₂ containing methanol andfinally it was held for 1 hour in a stream of pure N₂ at 150° F. Thecatalyst was subsequently heated to 1000° F in N₂ and held for 2 hoursat 1000° F in air. The calcined catalyst in one containing 5% CoO, 18%MoO₃, 1% P₂ O₅ and 76% Al₂ O₃. The catalyst had a surface area of 282 m²/g and a pore volume of 0.93 cc/g and contained excessive macroporositysimilar to the first catalyst. This catalyst was designated IE-20721.

A third catalyst was prepared idential to IE-20721 except for the dryingstep. When the surface had become essentially free of surface methanol,the impregnated catalyst containing methanol in the pores was immersedin hexanol at room temperature. It was allowed to equilibrate for 1 hourto partially displace the methanol from the pores. The catalyst was thenplaced in a tube and heated from 72° F to 150° F at 1° F/min. under aflowing stream of N₂ containing 17 vol.% methanol. Next, it was heatedat 1° F/min. from 150° F to 250° F in N₂ containing ca. 3% water vapor.The water was added because it was noted that water was evolving at thispoint, the water obviously having been produced from water hydrated withthe Al₂ O₃ and the water of crystallization of the cobalt and molybdenumsalts. Finally, the catalyst was heated from 250° F to 300° F at 1°F/min. in a flowing stream of N₂ containing ca. 1% C₆ OH. The catalystwas held at 150°, 250° and 300° F for 1 hour between each of thesesteps. Finally, at 300° F it was held for 1 hour in a flowing stream ofpure N₂. The catalyst was subsequently heated to 1000° F in N₂ and heldfor 2 hours followed by calcining in air for 2 hours at 1000° F. Thecatalyst had a surface area of 299 m² /g and a pore volume of 0.94 cc/gand contained excessive macroporosity. This catalyst was designatedIE-20781.

These catalysts were then tested to determine their hydrodesulfurizationand demetallization activities as described by reference to Example 2.The results are as tabulated below:

    ______________________________________                                        Catalyst       IM-20081  IE-20721  IE-20781                                   ______________________________________                                        Relative Activity                                                             after ca. 10 Days                                                             Hydrodesulfurization                                                                         66        70         78                                        Vanadium Removal                                                                             70        85        119                                        ______________________________________                                    

Note the prior art catalyst IM-20081 gave the poorest results. IE-20721which represents a catalyst prepared by improved impregnation(incremental Co/Mo addition) and slow drying resulted in improvedperformance. Lastly, IE-20781 which is a further improvement on the slowdrying stage (replacement of methanol with hexanol) shows furtherimprovement.

The following example shows that the regimen of restrictive dryingconditions required in Example 4 can be relaxed if essentially all ofthe low molecular weight solvent is replaced by a higher molecularweight, low vapor pressure solvent. In addition, the example furtherdemontrates that even with optimum impregnation and drying conditionsand low macroporosity giving good hydrodesulfurization activitymaintenance, the overcompression of the extrudate such as to reduce thenumber of 200-400A pores will result in poor demetallizationperformance. Only the catalyst of Example 2, having all of the requiredporosity properties in addition to good impregnation and dryingconditions, will result in a catalyst with an optimum balancedhydrodesulfurization and demetallization performance.

EXAMPLE 6

An extrusion paste was prepared by taking 100 gm of the spray-driedalumina of Example 1, and blending this material with 15 cc of water and5 drops of acetic acid, the acid being added as an extrusion aid. Thepaste was mulled by mortar and pestle and then remulled by extrusion,i.e., passage through a 3/16-inch drill die at 100 RPM. The remulledmaterial was then extruded through a 1/16-inch drill die having one holeand a land length 5/8 -inch, at an RPM maintained at 100. The extrudateswere air-dried for 15 minutes, extracted in isopropyl alcohol at 180° Ffor one hour, and then extracted in hexanol at 280° F for one hour. Theextracted extrudates were calcined for 2 hours in N₂ at 1000° F and for2 hours at 1000° F in air. The properties of these calcined extrudates,referred to as Sample EB-10403, are given in Table VI, Column 2, below.

Referring to Table VI, Column 2, as is evident from the data, excessivecompaction of the extrudates resulted. Although low 400A+ and 1000A+macroporosity resulted, the Sample EB-10403 alumina extrudates possesstoo low 200-400A pore volume which is needed for good demetallization.Two catalysts were made from the Sample EB-10403 material: Catalyst 6Aand Catalyst 6B. The other two catalysts 6C and 6D were prepared byimpregnating the extrudates described in Example 4(a) (EB-10353).

a. Catalysts 6A and 6C were each prepared in identical manner, asfollows: 21 gm of the alumina base (EB-10403) was air-exposed overnightto equilibrate with the moisture in the air. Each sample was then placedin 80 cc of methanol. Instead of adding the cobalt and molybdenum saltsall at once to the excess solvent, the salts were added incrementally tominimize formation of large crystallites at the pore mouths of thecatalyst particles. Cobalt nitrate was added in three successive 1.69 gmincrements, one increment each over a three-hour period, and thenphosphomolybdic acid was added in four successive 1.56 gm increments,one increment each over a four-hour period. Each of the catalysts wasthen simmered in hexanol at 280° F for 1 hour to completely displace themethanol of the catalysts with hexanol, providing final catalystscontaining 5% CoO, 18% MoO₃, 1% P₂ O₅ and 76% Al₂ O₃. The catalysts wereallowed to stand for 17 hours and then dried at room temperature untilonly a small amount of surface hexanol remained. The catalysts were thensimmered in hexanol at 280° F for 1 hour to completely displace themethanol with hexanol. Each catalyst was then calcined in N₂ for 2 hoursat 1000° F, then in air for 2 hours at 1000° F.

In the foregoing, no special precautions such as slow heatup (1° F/min)or solvent in the sweep N₂ were utilized to assure slow evaporation ofthe hexanol from the pores. The presence of the low vapor pressurehexanol in the pores was considered sufficient to assure slowevaporation.

b. Catalysts 6B and 6D were prepared in a manner identical to Catalysts6A and 6C except that the methanol containing alumina base, which hadbeen surface-dried overnight, was immersed in hexanol at roomtemperature. The catalysts were then allowed to equilibrate for 1 hourto partially displace the methanol from the pores. The catalysts wereeach then placed in a tube and heated from 72° F to 150° F at 1° F/min.under a flowing stream of N₂ containing 17 vol. % methanol. Thecatalysts were then held at this temperature for 1 hour. Next, thecatalysts were heated at 1° F/min. from 150° F to 250° F in N₂containing ca. 3% water vapor. Water was added to the nitrogen becauseit was noted that some water was being evolved at this point, the sourceobviously having been the water hydrated with Al₂ O₃ and the water ofcrystallization of the Co/Mo salts. The temperature, at the end of theperiod, was maintained at 250° F in the flowing stream for 1 additionalhour. The catalyst was then heated from 250° to 300° F at 1° F/min. in aflowing stream of N₂ containing ca. 1% hexanol. The temperature was thenheld at 300° F for 1 hour in a flowing stream of pure N₂. The catalystwas subsequently heated to 1000° F in N₂ and held for 2 hours, this stephaving been followed by calcining in air for 2 hours at 1000° F. Thesesteps were taken to assure slow evaporation of the solvent(s) from thepores since complete replacement of methanol with hexanol had not beeneffected.

The properties of Catalysts 6A, 6B, 6C and 6D are given in Table VI.

                  TABLE VI                                                        ______________________________________                                        Catalyst   EB-10403 6A     6B   EB-10353                                                                             6C   6D                                ______________________________________                                        Surface Area .sup.(1),                                                                   427      318    305  345    288  294                                m.sup.2 /g                                                                   Pore Volume .sup.(2),                                                                    1.19     0.82   0.85 1.18   0.99 0.96                               cc/g                                                                         Pore Volume .sup.(3),                                                                    1.21     1.07   0.85 1.18   0.99 0.97                               cc/g                                                                         PSD, cc/g PV .sup.(4)                                                          in                                                                           100-200A   0.53     0.56   0.47 0.49   0.46 0.48                              200-400A   0.09     0.01   0.01 0.16   0.10 0.10                               400A+     0.03     0.03   0.03 0120   0.13 0.13                              1000A+     0.02     0.02   0.02 0.17   0.11 0.11                              ______________________________________                                         .sup.(1) As measured by single point adsorption using BET equation.           .sup.(2) Single point nitrogen adsorption obtained by filling of pores.       .sup.(3) Pore volume as measured by Digisorb Desorption test, described       later.                                                                        .sup.(4) Measured by combination of Digisorb Desorption and Mercury           Intrusion.                                                               

These catalysts were tested as 14-35 mesh materials, and contrasted withthe Standard ethylene oxide catalyst at similar conditions, inprocessing a Cold Lake petroleum crude fed as previously described inExample 2, with the following results:

    ______________________________________                                        Catalyst     6A       6B       6C     6D                                      ______________________________________                                        Relative Activity                                                             after 9 Days                                                                  Hydrodesulfurization                                                                       117      117      72     72                                      Activity                                                                      ______________________________________                                    

These data show that the low macroporosity of Catalysts 6A and 6Bproduced good hydrodesulfurization activity maintenance, this beingsharply contrasted with the poor hydrodesulfurization performance ofCatalysts 6C and 6D which have high macroporosity. Catalysts 6A and 6B,however, were found to possess inferior demetallization performance dueto the low pore volume in 200-400 A pores. This example further showsthat by replacing all of the methanol in the pores of a catalyst withhexanol prior to drying simplifies the procedure in that no specialprecautions are required to insure slow vaporization from the pores ofthe catalyst. This is because this solvent has low volatility.

The following example shows that a catalyst essentially equivalent tothe standard ethylene oxide catalyst can be made by hydrogelimpregnation. Hydrogel impregnation assures and good dispersion of themetals due to the interaction of the metals with the alumina at anatomic level, rather than depending entirely upon slow drying in theterminal impregnation step to form small crystallites on the surface ofthe calcined alumina. Although it is believed that the crystallite sizeis set at the impregnation step, slow drying is nonetheless necessary inthe final calcination step to avoid reagglomeration of the metals on thesurface.

EXAMPLE 7

An alumina hydrogel was prepared as in Example 1 except no polymer wasadded and the material was not spray-dried. A 64,900 gram portion of thehydrogel, which contained 3.8% alumina solids, was blended with 509 gmsof cobalt chloride and 770 gm of phosphomolybdic acid. The blendedmaterial was then held for 4 hours and then blended with 3700 gm ofpolyethylene glycol having an average molecular weight of 300. Thematerial was held overnight at a temperature of 190° F. After overnightdrying (ca. 16 hours), the sample was extracted with isopropyl alcoholat 160°-170° F for 1 hour. The material was then air-dried for 30minutes, and thereafter for 2 hours at 190° F. At the end of this periodthe solids content was 54.5%. Sufficient water was then added to make apaste containing 36% solids, and a minimum quantity of acetic acid wasadded as an extrusion aid. The material was first mulled with a mortarand pestle, then extruded using the 3-hole, 1/16-inch drill die at 100RPM. The extrudates, after air-drying for 15 minutes, were treated withhexanol at 260° F for 1 hour to further extract the polymer and todisplace the water from the pores. This was done to assure slow dryingin the final calcination. The catalyst was calcined at 600° F for 1 hourin N₂, then at 1000° F for 2 hours in N₂, and finally at 1000° F for 2hours in air. The properties of this catalyst, referred to below asCatalyst 7A, are given in Table VII below:

                  TABLE VII                                                       ______________________________________                                        Surface Area .sup.(1), m.sup.2 /g                                                                 343                                                       Pore Volume .sup.(2), cc/g                                                                        0.81                                                      Pore Volume .sup.(3), cc/g                                                                        0.83                                                      PSD, cc/g PV in .sup.(4)                                                      100-200A            0.38                                                      200-400A            0.06                                                      400A+               0.04                                                      1000A+              0.02                                                      ______________________________________                                         .sup.(1) As measured by single point adsorption using BET equation.           .sup.(2) Single point nitrogen obtained by filling of pores.                  .sup.(3) Pore volume as measured by Digisorb Desorption test, described       later.                                                                        .sup.(4) Measured by combination of Digsorb Desorption and Mercury            Intrusion.                                                               

It will be observed, on the one hand, that the 200-400A pore volume islow. On the other hand, the 100-200A pores are at an acceptable level.The macroporosity pore volumes are also acceptable for a good heavy feedconversion catalyst with balanced hydrodesulfurization anddemetallization activities. Catalyst 7A, though somewhatoff-specification, was tested in Cold Lake crude at conditionspreviously described in Example 2, and the results are shown below:

    ______________________________________                                                       Standard                                                                      Ethylene                                                                      Oxide                                                          Catalyst       Catalyst    Catalyst 7A                                        ______________________________________                                        Relative Activity                                                             after 9 Days                                                                  Hydrodesulfurization                                                                         100         95                                                 Vanadium Removal                                                                             100         93                                                 ______________________________________                                    

Results of this test show, within the precision of the test, thatCatalyst 7A is almost the equivalent of the standard ethylene oxidecatalyst, and also a terminally impregnated PEG catalyst. This boost inactivity is sharply contrasted with that which would be expected of acatalyst with similar characteristics prepared by the conventionalimpregnation of a polymer-extended catalyst.

It is apparent that various modifications can be made in the conditionsof operation, the precise nature of the feed and catalyst compositions,and the like, without departing the spirit and scope of the invention.

Pore size distributions, as percent of total pore volume for purposes ofthe Sawyer et al and Robson applications, supra, are measured at variouspressures using the Aminco Adsorptomat Cat. No. 4-4680, and multiplesample accessory Cat. No 4-4685. The detailed procedure is described inthe Aminco Instruction Manual No. 861-A furnished with the instrument. Adescription of the Adsorptomat prototype instrument and procedure isgiven in Analytical Chemistry, Volume 32, Page 532, April, 1960.

An outline of the procedure is given here, including sample preparation.

From 0.2 to 1.0 g. of sample is used and the isotherm is run in theadsorption mode only. All samples are placed on the preconditionerbefore analysis where they are out-gassed and dried at 190° C undervacuum (10⁻⁵ Torr) for 5 hours. After pretreatment, the weighed sampleis charged to the Adsorptomat and pumped down to 10⁻⁵ Torr. At thispoint, the instrument is set in the automatic adsorption mode to chargea standard volume of gas to the catalyst. This is done by charging apredetermined number of volumes as doses and then allowing time foradsorption of the nitrogen to reach equilibrium pressure. The pressureis measured in termns of its ratio to the saturation pressure of boilingliquid nitrogen. Three doses are injected and 8 minutes allowed forequilibration of each measured relative pressure. The dosing andequilibration are continued until a pressure ratio of 0.97 is exceededand maintained for 15 minutes. The run is then automatically terminated.

The data obtained with the dead space factor for the sample, the vaporpressure of the liquid nitrogen bath, and the sample weight are sent toa digital computer which calculates the volume points of the isotherm,the BET area, and the pore size distribution of the Barret, Joyner, andHalenda method. [Barrett, Joyner, and Helenda, J. Am. Chem. Soc. 73, p.373.] It is believed that the Barrett, Joyner, and Halenda method is ascomplete a treatment as can be obtained, based on the assumptions ofcylindrical pores and the validity of the Kelvin equation.

Pore size distributions, as cc/gm of pore volume, for purposes of thepresent invention are measured by a combination of nitrogen desorptionusing the Digisorb 2500 and mercury injection using a MacromeriticsInstrument Co. 50,000 lb. Model Porosimeter. Studies on the Adsorptomatand Digisorb 2500 in the adsorption mode have shown both instruments tobe reproducible and reliable as "fingerprints" of the catalyst, but thepore size distributions obtained were somewhat larger in size using theAdsorptomat. This is though to result because the Adsorptomat does notalways reach "equilibrium" pressure during the nitrogen dosingprocedure. In addition to this factor, it is felt that the controllingpore size for diffusion is the pore mouth, thus nitrogen desorption andmercury intrusion should be more representative of this pore size. Withsome catalysts, mercury intrusion can be used to characterize the poresize distribution from 42A to ca. 200,000A in pore diameter. For higherpore volume catalysts (> ca 0.7 cc/gm) the high pressure exerted on themercury tube crushed the catalyst giving spurious results. To avoid theproblem, a combination of nitrogen desorption and mercury intrusion isused. In the region of 100 to 200A pore diameter, the pore volume curves(cc/gm pore volume vs. pore diameter A) either cross or parallel oneanother. At this junction, the two curves are joined. In so doing, thenitrogen desorption curve is considered reliable over the region of 20Ato ca. 150A pore diameter and the mercury injection over the range ca.150A to ca. 200,000A pore diameter. For purposes of this invention, thecombination method is utilized. Data from the Adsorptomat are includedfor comparison purposes to show that the catalysts of the presentinvention differ from prior art catalysts.

To obtain the pore volume distribution in the > ca. 150A region,measurements were made by mercury injection using a MicromeriticsInstrument Co. 50,000 lb. Model Porosimeter. Increments of pore volumewere observed at increasing pressure and related to pores being intrudedby the equation:

    PD = 3σ  cos θ

where P is the applied pressure, D the diameter of the pore, σ thesurface tension of mercury, and θ the contact angle between mercury andthe material forming the pore opening. The surface tension of mercury(σ) was taken to be 474 dynes/cm and the contact angle (θ) as 140°.

The measurement of the pore volume distribution in the region < ca. 150Awas made by the Micromeritics Digisorb 2500 automatic surface area andpore volume analyzer. The detailed procedure is described in theDigisorb Instruction Manual of June 3, 1974. An outline of the procedureis given here, including sample preparation. From 0.1 to 0.2 gm sampleis used and is out-gassed at 150° C for 6 hours at about 10⁻⁵ Torr.After degassing, the weighed sample is repressured to atmosphericpressure with helium, transferred to the analysis ports of theinstrument and pumped down to 10⁻⁵ Torr. The unit is then placed in theautomatic mode for measurement of the desorption isotherm. This is doneby the gradual addition of nitrogen to the catalyst until near tosaturation pressure (P/Po = ca. 0.99). "Equilibrium" saturation pressureis attained by repeated addition of nitrogen at decreasing rates until"equilibrium" is established. Since complete theoretical equilibrim willrequire an infinite time to establish, a practical "equilibrium" isestablished when 7 consecutive pressure measurements, each taken at6-second intervals, differ from the average pressure by 0.1% or less.

After establishing "equilibrium" saturation pressure, desorption isstarted and measurements obtained at preselected P/Po points. Thedesorption is carried out at 21 points, ending at a relative pressure of0.2 (P/Po = 0.2). At each point, "equilibrium" is checked by theprocedure noted above. Seven consecutive pressure measurements takenover 6-second intervals must not differ from the average pressure bymore than 0.1%. At the completion of the desorption process, the test isautomatically terminated and the samples are backfilled with helium toatmospheric pressure. A digital computer calculates the pore sizedistribution by the method of Barrett, Joyner and Halenda.

Data reported in the invention include (1) the surface area as measuredby the familiar single point N₂ adsorption method using the BETequation, (2) pore volume as measured by the familiar technique of asingle point measurement where all of the pores are filled with N₂, and(3) the pore volume distribution obtained by combination of N₂desorption and mercury intrusion as reported above. Additionally, atotal pore volume is reported which is obtained from the N₂ desorptionpore volume distribution curve.

Having described the invention, what is claimed is:
 1. In a process forthe formation of a catalyst comprised of a Group VI-B or Group VIIImetal, or both, composited with alumina in a series of steps whichincludeprecipitating alumina hydrogel from a solution which contains ahydrous form of alumina in concentration ranging from about 1 to about 5percent, based on the weight of the solution, and a compound having ananion which forms an alkaline soluble aluminum salt in an alkalinemedium, at temperatures ranging from about 15° F. to about 120° F. andpH ranging from about 8 to about 12, separating said alumina hydrogelfrom said alkaline solution, contacting said alumina hydrogel with asolution of a water soluble polymer containing from about 2 to about 24monomer units from the group consisting of (a) polyethylene glycols, (b)polypropylene glycols, and (c) polyethylene amines sufficient to absorbthe polymer into the pores of the alumina hydrogel and displace waterfrom the pores until the weight ratio of polymer: alumina within thehydrogel ranges from about 0.5:1 to about 4:1, forming a slurry of thepolymer containing alumina hydrogel, spray drying said slurry of polymercontaining alumina hydrogel by countercurrent contact of an atomizedspray of the alumina hydrogel with air at temperature sufficient to formgranules of boehmite, forming a paste from the granules of polymercontaining boehmite and water, the paste containing at least about 20percent by weight of solids, and mulling said water soluble polymercontaining boehmite paste to provide a substantially homogeneous mass,the improvement comprising: extruding said polymer containing boehmitepaste through a die to form spaghetti-like extrudate shapes by applyinga torque ranging from about 25 to about 55 inch pounds, sizing andshaping the boehmite, contacting and extracting said boehmite shapeswith a solvent to separate and remove the water soluble polymertherefrom, and then drying and calcining the shapes, and converting theboehmite shapes from which the polymer has been extracted to gammaalumina.
 2. The process of claim 1 wherein the Group VIB or Group VIIImetal, or both, is composited with the alumina by impregnation of thealumina hydrogel with a solvent containing a compound, or compounds, ofthe Group VIB or Group VIII metal, or both.
 3. The process of claim 1wherein the Group VIB or Group VIII metal, or both, is composited withthe dried, calcined gamma alumina shapes.
 4. The process of claim 1wherein, (a) when the catalyst ranges from about 1/50 inch up to about1/25 inch particle size diameter, it is characterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          200-500                                                   Pore Volume, cc/g   0.5-1.5                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.3                                                      200-400A             >0.05                                                     400A+              <0.2                                                      1000A+              <0.1                                                      ______________________________________                                    

and (b) when the catalyst ranges from about 1/25 inch up to about 1/8inch particle size diameter, it is characterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 2/g                                                                         200-500                                                   Pore Volume, cc/g   0.7-1.7                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.3                                                      200-400A             >0.05                                                    400A+               <0.2                                                      100A+               <0.1                                                      ______________________________________                                    


5. The process of claim 1 wherein, (a) when the catalyst ranges fromabout 1/50 inch up to about 1/25 inch particle size diameter, it ischaracterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          225-325                                                   Pore Volume, cc/g   0.7-1.1                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.4                                                      200-400A            >0.1                                                      400A+               <0.1                                                      100A+                <0.05                                                    ______________________________________                                    

and (b) when the catalyst ranges from about 1/25 inch up to about 1/8inch particle size diameter, it is characterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          250-350                                                   Pore Volume, cc/g   0.8-1.3                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.4                                                      200-400A            >0.01                                                     400A+               <0.1                                                      1000A+               <0.05                                                    ______________________________________                                    


6. The process of claim 1 wherein the extrudate shapes are contactedwith solvent to extract the polymer, then dried and calcined to formgamma alumina.
 7. The process of claim 6 wherein the Group VIB or VIIImetal, or both, is composited with the dried, calcined, gamma aluminaextrudate shape.
 8. The process of claim 7 wherein (a) when the catalystranges from about 1/50 inch up to about 1/25 inch particle sizediameter, it is characterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          200-500                                                   Pore Volume, cc/g   0.5-1.5                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.3                                                      200-400A             >0.05                                                     400A+              <0.2                                                      1000A+              <0.1                                                      ______________________________________                                    

and (b) when the catalyst ranges from about 1/25 inch up to about 1/8inch particle size diameter, it is characterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          200-500                                                   Pore Volume, cc/g   0.7-1.7                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.3                                                      200-400A             >0.05                                                     400A+              <0.2                                                      1000A+              <0.1                                                      ______________________________________                                    


9. The process of claim 7 wherein (a) when the catalyst ranges fromabout 1/50 inch up to about 1/25 inch particle size diameter, it ischaracterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          225-325                                                   Pore Volume, cc/g   0.7-1.1                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.4                                                      200-400A            >0.1                                                       400A+              <0.1                                                      1000A+               <0.05                                                    ______________________________________                                    

and (b) when the catalyst ranges from about 1/25 inch up to about 1/8inch particle size diameter, it is characterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          250-350                                                   Pore Volume, cc/g   0.8-1.3                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.4                                                      200-400A            >0.1                                                       400A+              <0.1                                                      1000A+               <0.05                                                    ______________________________________                                    


10. The process of claim 1 wherein the spaghetti-like extrudate shapesare dried, marumerized to form spheres, contacted with solvent toextract the polymer, dried and calcined to form gamma alumina spheres,which (a) when the spheres range from about 1/50 inch up to about 1/25inch particle size diameter, are characterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          200-500                                                   Pore Volume, cc/g   0.5-1.5                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.3                                                      200-400A             >0.05                                                     400A+              <0.2                                                      1000A+              <0.1                                                      ______________________________________                                    

and (b) when the spheres range from about 1/25 inch up to about 1/8 inchparticle size diameter, they are characterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          200-500                                                   Pore Volume, cc/g   0.7-1.7                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.3                                                      200-400A             >0.05                                                     400A+              <0.2                                                      1000A+              <0.1                                                      ______________________________________                                    


11. The process of claim 10 wherein (a) when the spheres range fromabout 1/50 inch up to about 1/25 inch particle size diameter, they arecharacterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          225-325                                                   Pore Volume, cc/g   0.7-1.1                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.4                                                      200-400A            >0.1                                                       400A+              <0.1                                                      1000A+               <0.05                                                    ______________________________________                                    

and (b) when the spheres range from about 1/25 inch up to about 1/8 inchparticle size diameter, are characterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          250-350                                                   Pore Volume, cc/g   0.8-1.3                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.4                                                      200-400A            >0.1                                                       400A+              <0.1                                                      1000A+               <0.05                                                    ______________________________________                                    


12. The process of claim 10 wherein the Group VIB or VIII metal, orboth, is composited with the dried, calcined gamma alumina spheres. 13.The process of claim 1 wherein the alumina hydrogel is precipitated bycombining solutions (a) a first of which contains an alkali metalaluminate and (b) a second of which contains a strong mineral acid or analuminum salt of a strong mineral acid, the anion portion of which issoluble in the alkaline solution.
 14. The process of claim 1 whereinsilica is added to the solution.
 15. The process of claim 1 wherein thetemperature of precipitation ranges from about 32° F to about 70° F. 16.The process of claim 1 wherein the concentration of alumina containedwithin the solution ranges from about 2 to about 3 percent, based on theweight of the solution.
 17. The process of claim 1 wherein the pH of thesolution ranges from about 9 to about
 10. 18. The process of claim 1wherein the precipitated alumina hydrogel is washed at ambienttemperature.
 19. The process of claim 1 wherein the hydrogel is washedat temperatures ranging from about 70° F to about 85° F.
 20. The processof claim 1 wherein the water soluble polymer contains from about 4 toabout 8 monomer units in the total molecule.
 21. The process of claim 1wherein the polymer displaces water from the pores of the aluminahydrogel until the weight ratio of polymer:alumina within the hydrogelranges from about 1:1 to about 2:1.
 22. The process of claim 1 whereinthe polymer containing alumina hydrogel is spray dried at airtemperatures ranging from about 250° to about 350° F to form theboehmite, the temperature of the boehmite per se being maintained belowabout 250° F.
 23. The process of claim 22 wherein the polymer containingalumina hydrogel is spray dried at air temperatures ranging from about275° to about 300° F.
 24. The process of claim 22 wherein the boehmiteis formed as a granulated solid of average particle size diameterranging from about 75 to about 125 microns.
 25. The process of claim 22wherein, after the spray drying step, granulated boehmite is formed, andwater is added back to the boehmite to form an extrudable homogeneouspaste.
 26. The process of claim 25 wherein the extrudable homogeneouspaste contains from about 26 to about 32 weight percent alumina.
 27. Theprocess of claim 25 wherein the granulated boehmite paste is extruded byapplying a torque ranging from about 40 inch-pounds to about 50inch-pounds, the solids content of the extrudable homogeneous paste iscontrolled, and the relationship between the solids content of thepaste, extrudate diameter and the average spherical size diameter of thespherical particles to be ultimately formed from extrudates are asfollows:

    ______________________________________                                        Solids Content                                                                            Extrudate      Average Sphere                                     of the Paste,                                                                             Diameter,      Size Diameter,                                     Wt. %       Inches         Inches                                             ______________________________________                                        30-32       1/55-1/28      1/50-1/25                                          28-30       1/32-1/21      1/25-[1/6] 1/16                                    26-28       1/24-1/12      1/16-1/8                                           ______________________________________                                    


28. The process of claim 27 wherein the spheres are dried, calcined toform gamma alumina and the Group VIB or VIII metal, or both, iscomposited with the gamma alumina spheres.
 29. The process of claim 28wherein (a) when the spheres range from about 1/50 inch up to about 1/25inch particle size diameter, they are characterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          200-500                                                   Pore Volume, cc/g   0.5-1.5                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.3                                                      200-400A             >0.05                                                     400A+              <0.2                                                      1000A+              <0.1                                                      ______________________________________                                    

and (b) when the spheres range from about 1/25 inch up to about 1/8 inchparticle size diameter, are characterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          200-500                                                   Pore Volume, cc/g   0.7-1.7                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.3                                                      200-400A             >0.05                                                     400A+              <0.2                                                      1000A+              <0.1                                                      ______________________________________                                    


30. The process of claim 28 wherein (a) when the spheres range fromabout 1/50 inch up to about 1/25 inch particle size diameter, they arecharacterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          225-325                                                   Pore Volume, cc/g   0.7-1.1                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.4                                                      200-400A            >0.1                                                       400A+              <0.1                                                      1000A+               <0.05                                                    ______________________________________                                    

and (b) when the spheres range from about 1/25 inch up to about 1/8 inchparticle size diameter, are characterized as follows:

    ______________________________________                                        Surface Area, m.sup.2 /g                                                                          250-350                                                   Pore Volume, cc/g   0.8-1.3                                                   Pore Size                                                                     Distributions, cc/g                                                           100-200A            >0.4                                                      200-400A            >0.1                                                       400A+              <0.1                                                      1000A+               <0.05                                                    ______________________________________                                    